What is the answer to this question?

The answer is C.

Explanation:

This is because for A, this statement says nothing about corundum being yellow which means that this doesn’t apply and is incorrect. For B is pretty much the same as A, this statement about corundum doesn’t say anything about it being able to flavor or being flavorful. Lastly for D, the fact that corundum is hard means it would be impractical and probably impossible to use it as pencil lead because, all lead it doing with a pencil is being crushes and ground into the paper as you write.

Hope this helps.

they had the law tat factories that produces smoke cannot be built near residential buildings.

building of proper sewage system was done to ensure that the waste is carried away from the humans so that they do not get diseases from it.

also they built water systems to provide water in those areas which are drought prone.